Light transfer devices using light conducting members of multilayered construction and photoelectric means



W SEARCH 1109M AND PHOTOELECTRIC MEANS '7 Sheets-Sheet 1 mm m E. E.SHELDON W k QW WW l l l l a BED-"95 9269 NR 3p-+99q l07 March 3, 1970LIGHT TRANSFER DEVICES USING LIGHT CONDUCTING MEMBERS OF MULTILAYEREDCONSTRUCTION Original Filed Nov. 28, 1956 M 0 R D a $0 Q 9 mm Q WJ I L Ldmw QAN Qmw m w J, MN M fl fiw E w m :w

No oi'z pmss March 3, 1970 E. E. SHELDON 3,499,107

LIGHT TRANSFER DEVICES USING LIGHT CONDUCTING MEMBERS OF MULTILAYEREDCONSTRUCTION AND PHOTOELECTRIC MEANS Original Filed Nov. 28, 1956 7Sheets-Sheet 2 aw AW, IB M "1. {25 i a? .10 7 a CIRCU T Sol/(ct 0F Mall7 INVENTOR. [omwo [MIN/(A64. 60:40am

TTURNZZS March 3, 1970 E. E. SHELDON 3,499,107

LIGHT TRANSFER DEVICES USING LIGHT CONDUCTING MEMBERS OF MULTILAYEREDCONSTRUCTION AND PHOTOELECTRIC MEANS Original Filed Nov. 28, 1956 7Sheets-Sheet 3 tag m H 3 w 46 4a.

INVENTOR. [ow/m0 (Sm/mus L 5am 0am :TTUIWVEYS March 3, 1970 E. E.SHELDON 3,499,107

LIGHT TRANSFER DEVICES USING LIGHT CONDUCTING MEMBERS OF MULTILAYEREDCONSTRUCTION AND PHOTOELECTRIC MEANS Original Filed Nov. 28, 1956 7Sheets-Sheet 4 nan-"nun- ATTURN .5

March 3, 1970 E. E. SHELDON 3,499,107

LIGHT TRANSFER DEVICES USING LIGHT CONDUCTING MEMBERS OF MULTILAYEREDCONSTRUCTION AND PHOTOELECTRIC MEANS Original Filed Nov. 28, 1956 7Sheets-Sheet 5 I04 274 lll 3 276 Ma /a.

w" M w INVENTOR. foam/P0 [MM/U51. 5,951.00

March 3, 1970 E. E. SHELDON 3,499,107 LIGHT TRANSFER DEVICES USING LIGHTCONDUCTING MEMBERS OF MULTILAYERED CONSTRUCTION AND PHOTOELECTRIC MEANSOriginal Filed Nov. 28, 1956 7 Sheets-Sheet 6 J01 3015 M c +2 v .93 i?9' L90 5 j 95 66 3 7 3 0 "1 l :\'II IIIH\ a fl mm 97 6% 97 57 4/0 II IIII II II I Ill 23 1/3 7 11 g 45 23 7 INVENTOR. [ow/220 [MONUL S's/awayATTDIWE Y5 March 3, 1970 E. E. SHELDON 3,499,107

LIGHT TRANSFER DEVICES USING LIGHT CONDUCTING MEMBERS OF MULTILAYEREDCONSTRUCTION AND PHOTOELECTRIC MEANS Original Filed Nov. 28, 1956 7Sheets-Sheet '7 007m Chew/rs 152a 15a I m )1 l 1179 E I //0 7 AFB W525United States Patent M 3,499,107 LIGHT TRANSFER DEVICES USING LIGHT CON-DUCTING MEMBERS OF MULTILAYERED CON- STRUCTION AND PHOTOELECTRIC MEANSEdward Emanuel Sheldon, 30 E. 40th St.,

New York, N.Y. 10016 Application Dec. 4, 1961, Ser. No. 158,638, nowPatent No. 3,279,460, which is a division of application Ser. No.624,829, Nov. 28, 1956. Divided and this application Apr. 15, 1966, Ser.No. 542,918 Int. Cl. H04n 3/16 US. Cl. 178-6.8 11 Claims ABSTRACT OF THEDISCLOSURE The invention relates to novel light conducting devices andsystems using a source of light and one or a plurality of light guidingmembers which are characterized by the construction in which each ofsaid members has a core part of material of a high index of refractionand a peripheral part of material of a lower index of refraction thansaid core. In addition the above system comprised photosensitive meansfor receiving said conducted light. In some embodiments phototubes orphotosensors of solid-state type are used. In other embodiments a vacuumtube such as image reproducing tube or a television pick-u tube arepreferred.

This invention relates to novel photoelectric instruments for thetransfer of images, and represents a division of my copending Ser. No.158,638, filed Dec. 4, 1961, now US. Patent 3,279,460, issued on Oct.18, 1966, which was a copending division of Application No. 624,829,which is now US. Patent 3,021,834, filed Nov. 28, 1956. The aforesaidUS. 3,021,834 has a common subject matter and was co-pending with U8.Patent 2,877,368 filed Mar. 11, 1954.

The purpose of my invention is to intensify the image of the examinedinternal parts or passages so that the final image will be presented tothe observer with the luminosity facilitating inspection of said image.

Another objective of this invention is to change, decrease or amplifythe contrast of the image of the exam.- ined part.

Another purpose of my invention is to enable simultaneous observation bymany examiners of close or remote locations, which was not possibleuntil now.

Another purpose of my invention is to provide means for simultaneousvisual inspection, and photographic recording of the examined area whichalso has never been possible before.

Another purpose of this invention is to provide means for inspection ofinaccessible channels, such as hollow parts of machinery or of otherinaccessible tortuous passages. My device may be introduced inside of apart which cannot be inspected visually without dismantling ordestroying the whole machine and will transmit the image of said part tothe observer outside of said part. My invention will be especiallyuseful for the examination of coils and pipes or other curvedstructures. My device can be also used as a probe to be inserted into asolid object and to transmit information about its internal structure.

The objectives of my invention were realized by a novel device which isflexible to allow its introduction into the examined part regardless ofits curvatures or angulations and which after its introduction into theexamined part will produce a light image of said part. Video signals arereconverted in receivers outside of the examined part into visibleimages for inspection or recording. My intrascopic device can produceblack and white 3,499,107 Patented Mar. 3, I970 images, as well asmulticolor images, showing faithfully or arbitrarily the colors of theexamined part.

In particular this novel device besides other inventive features makesthe use of a television pick-up tube consisting of two separateindependent elements which can be introduced separately into theexamined part and which after introduction work in cooperation as atelevision camera. As each of these two separate elements is smaller insize than any conventional television camera can be made, this noveltelevision camera can be introduced into locations which, because ofsmall size or tortuous shape of passages leading to them, wereinaccessible to the most miniaturized television cameras known in theart.

Another marked improvement in my novel television camera is eliminationof magnetic deflecting and focusing coils which are bulky and occupy somuch space that even a small television tube using them cannot beintroduced into narrow passages. The use of conventional electrostaticdeflecting system results in a marked distortion of images especially inpick-up tubes using the slow scanning electron beam. These drawbacks areeliminated in my intrascope and therefore in spite of its very smallsize it is capable of producing images of a good definition andcontrast.

FIGURE 1 represents a partially sectioned view of the novel instrumentfor inspection of inaccessible parts;

FIGURE 1a shows a modification of the intrascope;

FIGURES 1A, 1B, 1C and 1D show modifications of the image sensitivemember;

FIGURE 1b shows the intrascope in combination with the pushing guide forintroduction of component parts of the television camera into theintrascope;

FIGURE 2 shows the intrascope provided with a modification of thetelevision camera;

FIGURES 2a, 2b and 2c represent modifications of the television camera;

FIGURES 2d and 2e represent a cross-sectional perspective view ofsupporting element for the composite target in the television camera;

FIGURE 3 shows a modification of the intrascope having an opticalsystem;

FIGURE 4, 4a and 4b show simplified cameras for the intrascope;

FIGURE 5 shows an intrascope without illuminating source;

FIGURE 5a is a simplified form of intrascope shown in FIGURE 5;

FIGURE 6 represents an intrascope for producing color lmages;

FIGURE 6a represents color disc;

FIGURE 7 represents a modification of the intrascope for color images;

FIGURE 7a represents a simplified form of an intrascope for colorimages;

FIGURE 8 represents an intrascope sensitive to invisible images;

FIGURES 8a and 8b represent a modification of pick-up tube;

FIGURE 9 shows a novel flexible flying spot tube;

FIGURES 9a, 9b and show modifications of the flexible flying spot tube;

FIGURE 10 shows a modification of the endoscope having flexible vacuumtube;

FIGURES 11 and 12 show a novel flexible television pick-up tube;

FIGURES 13, 14, 15 show a novel endoscope having image conductor;

FIGURES 15a, 15b, 15c and 15d show modifications of the novel endoscopewith image conductor;

FIGURE 16 shows a novel flexible light source;

FIGURE l7 shows a novel vacuum tube having a telescopic electron gun.

This new device which may be called the intrascope or endoscope 1 isshown in FIGURE 1. The handle 2 is a hollow tube of diametercorresponding to the examined part. The handle may be rigid orsemi-flexible or completely flexible according to the part to beexamined. At the end of the handle begins the flexible part 2a of theintrascope which also has width and length suitable for the size of theexamined part. In case the intrascope is used for examination of fragileparts, the part 2a must be very flexible and pliable in order to avoiddamage to the wall of the examined part. This basic feature of thematerial for the flexible part of the intrascope is therefore that itmust be easily bent and molded by the walls of the passages in which itis being introduced. Such material may be rubber 26 or a suitableplastic, of the type used by Davol Rubber Company of Providence, RI. Incase the intrascope is used for investigation of sturdy parts or ofmachinery, the part 2a may be more rigid. The flexible part 2a of theintrascope may be in such a case made of the stainless steel spiralsheet designed not only for durability but also to maintain the properdegree of flexibility and elasticity. The metal spiral is tapered toinsure its uniform bending. The intrascope may be covered with an outertubing 26a such as of neoprene. This prevents dust particles andmoisture from affecting the optical and pick-up system located inside ofthe intrascope. At the end of the flexible part there is a semi-flexibletip 3 which may be screwed on the flexible part and can be easilyremoved giving thereby access to the inner structures of the intrascope.The tip consists of a rubber conical finger and serves to facilitate thegliding of the intrascope within the examined part. In order tofacilitate the introduction of the intrascope into parts which have nocurves, my device can be made semi-rigid by inserting into it asemi-rigid stilet. In case the intrascope is used as a probe forinsertion into a solid object, the tip 3 should preferably be rigid andsharply pointed to be able to pierce the examined object. In some casesthe tip is provided with one or more windows at its end to transmit thelight to the examined part and to receive the image of said part. Thetip may also have a semi-spherical or other shape.

In some cases the examined part has to be distended by air or fluidinsufllation prior to the examination. A special air pump attachment 44and a channel 44a in the intrascope is provided for this purpose. Thechannel 44a may also serve to evacuate contents of the examined partbefore examination to improve visibility. The knob 45 on the proximalend of the intrascope serves to indicate to the examiner the position ofwindows 12 and 18 of the intrascope. In examination of living bodies,the layer 26 or 2601 should be of a highly dielectric material toprevent any short circuits.

In the distal end of the flexible part of the intrascope there is ahousing box containing the illumination system 7. The box 5 may also beattached to the inner walls of the intrascope by means of the bracketsor may be held by springs. It is obvious that there are many means forattachment of the box 5 which are well known in the art. All walls ofthe housing box 5 except the one facing the television pick-up tube 16are provided with windows for transmission of the light from theilluminating system 7. These windows are correlated with the windows 12in the flexible part of the intrascope which transmit the light from theilluminating system to the examined part. In some cases the windows 12may be made to extend over the circumference of the intrascope. In somecases the window to transmit illumination from the light source to beexamined part may also be provided in the distal end of the intrascopeinstead of being in its side walls, and in such case the tip may be madeof transparent material or may be omitted. Windows 12 may be providedwith shutters which can be controlled from the proximal end of theintrascope which is outside of the examined art.

p The illuminating system may consist of the electrical bulb 7. Theelectrical bulb may be mounted in the housing box 5 by means of a socket7a. In some cases it is advantageous to use the objective lens 11between the light bulb and window 12 in order to concentrate the lighton one field. The lens may be held in position by brackets 11a. Thelight bulb is activated by the source of electrical power 9 situatedoutside of the examined part. Such a source may be the commercialelectrical current or battery of dry cells. The flexible electricalcable 8 leads from the socket 7a to said outside source of electricalcurrent 9. The cable is a lacquered, double insulated electric wire, iscovered in addition with liquid rubber and is vulcanized in order toprevent a short circuit. The housing unit 5 may be in some cases omittedand the light source may be attached to the socket 7a which is held bybrackets. In some cases electrical power of very high frequency ispreferable.

In the flexible part 26: proximally to the housing box 5, there is arigid non-transparent housing compartment 14 containing the opticalsystem 15 and the novel television pick-up tubes 16:: and 16b. Thehousing 14 has an opening 17 in which the optical system 15 is lodgedand which serves to admit the image of the examined part. This openingis correlated with windows 18 in the flexible art of the intrascopewhich transmit the image of the examined part. In some cases the windows18 may be made to extend over all the circumference of the intrascope.The windows 18 may be provided with shutters operated from the proximalend of the intrascope which is externally to the examined part. Thehousing 14 containing the television pick-up tubes 16a and 16b and theoptical system may be attached to the inner wall of the flexible part 2aof the intrascope by means of brackets or may be held by springs 27a. Asthe housing box fits into the encasing holding member 26 and is held byit tightly, in some cases no additional supporting means such as springsare necessary.

The optical system 15 may consist of 90 gable prism and of lens 21. Theoptical system may have its own housing unit instead of being lodge inthe compartment 14 and may then be introduced into the intrascope separately.

In some cases it is desirable to have a large field of vision and at thesame time to preserve the necessary demagnification of the examinedpart. In such case, instead of the prism 20, a rotating mirror should beused. The mirror has first surface coating which eliminates thereflections and is activated by the magnetic solenoid placed beneath themirror. The solenoid is connected by the elastic cable with the controlsoutside of the examined part and can tip the mirror from the retrogradeposition to the forward position, giving thereby an additional field ofvision without the necessity of moving the intrascope. The image of theexamined part is reflected by the mirror on the objective lens whichfocuses said image on the photocathode of the novel television pick-uptube 1611 described below. .In case the demagnification of the examinedpart is not necessary a large field of. vision can be obtained by usingthe lens providing 80 field of vision instead of the usual -50. Theimage produced by the optical system is inverted but it can be revertedto the original position either by an additional lens orelectronoptically in the viewing tube. The rotating mirror may alsoserve to admit image either through window 18 or 18a without rotatingthe whole camera 16.

The housing box contains the novel miniature television camera 16 whichwas designed to reduce to the minimum the size of the television camera.The television pick-up tubes known previously in the art could beminiaturized only to a certain degree, which was not sufli cient incertain applications as some of the examined parts are too small toallow the introduction even of the,

smallest conventional pick-up tube. This is true especially for the typeof tubes having external deflecting coils such as of magnetic orelectro-magnetic type, and in such situations, my novel camera 16 Willbe very suitable as it does not require any external deflecting orfocusing coils at all. The camera 16 consists of two vacuum tubes 16aand 16b. The tube 16a has an electron gun 28 which produces an electronbeam 29. The electron beam 29 is focused by electrostatic field 30. Theelectron-optical system for focusing the electron beam 29 may besimplified and markedly reduced in length by using the unipotentialelectrostatic lens instead of the usual two-lens system. The electronbeam 29 is deflected by electrostatic plates 30a and 30b in twoperpendicular to each other planes. The electrostatic plates areenergized by signals from sawtooth generals 32 which are situatedoutside of the examined part. The generators 32 are connected withelectrostatic plates 30a and 30b by means of flexible wires. Onedeflecting field is produced by the horizontal deflection plates 30a andmay have line frequency such as l5,000 cycles per second. Anotherdeflecting field is provided by the vertical deflection plates 30b andmay have field frequency such as l560 cycles per second. In this way theelectron beam 29 is made to scan the fluorescent screen 31 in a regulartelevision raster. The fluorescent screen 31 may be in some casesprovided with electron-transparent metallic conducting backing layer 31asuch as of aluminum. The fluorescent screen 31 must be of a phospher ofa very short persistence in order to obtain a good resolution of theimage. ZnO has decay time of 1 microsecond and is suitable for thispurpose. Still better results may be obtained by means of ZnO phospherand using only ultra-violet component of its fluorescent emission whichhas decay time of microsecond. In some cases, it is preferable to makethe fluorescent screen 31 of semi-spherical curved shape as it willimprove definition of the flying light spot. The fluorescent layer 31may also be deposited on a supporting mesh screen instead of beingdeposited on the wall of the vacuum tube. This will improve definitionof the flying light spot.

The vacuum tube 16a operates in combination with the vacuum tube 16bforming together the novel television camera 16. The vacuum tube 16b hasa photoemissive electrode 33 which may be deposited or attached to oneof the walls of said vacuum tube. In some cases it is preferable toprovide a light transparent conducting layer 33, such as of materialknown in the trade as Nesa, or of compounds of tin or of cadmium, on theside of said photoemissive electrode 33 facing the fluorescent screen31. Such a layer must be very thin, e.g., of the order of microns inorder not to impair the definition of images produced by the novelpick-up tube. The photoemissive electrode 33 may be of CsOAg or ofcaesium, sodium, lithium or rubidium on antimony, arsenic or bismuth, orof a mixture of aforesaid elements. At the opposite end of the vacuumtube 16b there is provided a photocathode 34 which consists of a lighttransparent signal phase 34a, a light transparent insulating layer 34band a photoemissive mosaic 340. The signal plate 34a may be a thintransparent layer of metal or other conducting material. The insulatinglayer 34b may be of mica, silica, or other transparent dielectricmaterial and photoemissive mosaic 340 may be of CsOAg or of caesium,rubidium, potassium or lithium on antimony, arsenic or bismuth, or of amixture of aforesaid elements. In some cases the photoemissive layer 340may be, instead of a mosaic, also of continuous type. In cases in whichelectrostatic focusing field 23 is used to focus the scanning electronbeam 33a on the mosaic 34c, much better resolution will be obtained bymaking such mosaic of curved semispherical shape. In addition, the useof such spherically shaped photocathode will eliminate instability ofthe image which is very marked when using electrostatic fields forfocusing a slow electron beam.

It should be understood that the photocathode or screen 34a may be ofphotoconductive or photovoltaic type. FIGURE 1A illustrates thephotoconductive type of the photocathode 34A which comprises alight-transparent conducting layer 34a and a photoconductive layer 34C.The photoconductive layer 34C may be of various sulphides, selenides,especially those containing zinc, cadmium or lead, of oxides such asPbO, CaO or ZnO, of tellurides, antimonides, especially containingindium or of compounds of titanium, such as barium or lead titanates. Insome cases a mixture of two or more of aforesaid elements will producebetter results. In some cases various activators like Cu or S are addedto the layer 34C to modify its characteristics. It should be understoodthat the photoconductive layer 34C may be an evaporated layer, sinteredlayer, a layer embedded in a plastic, a crystalline layer, a mosaic ofcrystals or a single crystal. In some cases a light-transparentdielectric layer may be provided between the layer 34a and 34C. Thephotocathode 34A may be of convex shape or of a planar shape.Furthermore, the layer 34a may be mounted on the side of thephotoconductive layer 34C which faces the electron beam. In addition theconducting layer 34a should be in some cases connected to a source of anelectrical potential to provide a biasing electrical field across thelayer 34C. The remaining parts of the tube 16B are the same as of thetube 16b.

The light image of the examined part is projected by the optical systemon the photocathode 34 of the vacuum tube 16b. The light image producesemission of photoelectrons from the layer 340. As a result, a positivecharge image having the pattern of said light image is left on thephotoemissive mosaic 340. Both vacuum tubes 16a and 16b are held inopposition to each other and in such a manner that the fluorescentscreen 31 of the vacuum tube 16a is adjacent to the photoemissiveelectrode 33 of the tube 16b. The scanning electron beam 29 impinging onthe fluorescent screen 31 produces a light spot at each point of itsimpingement. The scanning illumination excites the photoemissiveelectrode 33 and produces thereby a fine scanning beam of photoelectrons33a. The photoelectron beam 33a is of the scanning type because it isproduced by the scanning electron beam 29. The photoelectron beam 33amay be further focused by electrostatic fields 23. In this constructionit is preferable to use focusing fields because the separation of thefluorescent screen 31 from the photoemissive electrode 33 by thethickness of the wall of the vacuum tubes 16 and 16b causes certainunsharpness of the photoelectron beam 33. The electron beam 33a may beof high velocity such as used in the iconoscope type of televisionpick-up tubes or may be of a slow velocity. In this embodiment of myinvention, I use the slow scanning electron beam. It is to beunderstood, however, that the fast scanning electron beam may be used inmy invention as well. The electron beam 33a scanning across the chargeimage stored in the mosaic 34c converts said image into electricalsignals Which appear at the signal plate 34a. These electrical signalscan be converted into video signals over the resistance in the mannerwell known in the art. The video signals are transmitted by the flexiblecoaxial cable 43 from the intrascope within the examined part to thevideo amplifiers 43a outside of said part. The amplified signals aretransmitted from the amplifiers to the viewing tube of kinescope type3.7 and are reconstructed therein into the visible image representingthe image of the examined part. The viewing tube may be of kinescopetype and does not have to be described in detail as it is well known inthe art. The examined part will appear on the fluorescent screen 37a ofthe viewing tube where it can be inspected by many examiners.Transmission of the image from the amplifier 43a to the viewing tube canbe done by coaxial cable 43 or by high frequency Waves. The image can besent, therefore, not only to the immediate but also to the remotereceivers or may be transmitted to multiple independent viewing '7 tubesfor the benefit of many examiners, which was one of the objectives ofthis invention. The image on the view-' ing tube 37 may also bephotographed simultaneously with the intrascopic examination in order tomake a permanent record, which was another purpose of this invention. Itshould be understood that the electrical signals from the pickup tubemay be fed into various utilization circuits instead of into imagereproducing receivers.

The contrast of the reproduced image may be changed, diminished orincreased according to the needs of particular examination by usingamplifiers provided with variable mu tubes, or by the use of kinescopein which gamma can be controlled. The signal to noise ratio of thissystem and therefore the definition of the reproduced image may beimproved by using in amplifiers discrimination circuits which rejectsignals below the predetermined amplitude and eliminate therefore mostof the noise signals. The coaxial cable 43 within the examined part maybe encased in the above-described means 26 or 26a for insertingintrascope or may be attached to them.

The voltages for the operation of the tubes 16a and 16b are suppliedthrough the flexible electrical wires 8a from the source of theelectrical power 9 outside of the examination. In this same way thehorizontal and vertical syn chronizing circuits, focusing fields anddeflecting circuits are supplied with electrical energy from the outsidesource of power 9. The synchronizing circuits are not described indetail as they are well known in the art and it is believed they wouldonly complicate the drawings. In some cases the coaxial cable may beoutside of said inserting means 26 or 26a.

Another modification of the tube 16b is shown in FIG URE 1B. The tube16B has a composite photocathode 34B. FIGURE 1B shows a vacuum tubeprovided with one composite image-sensitive screen. The photocathode orscreen 348 has a photoemissive layer 123, a dielectric layer 124, aphotoconductive layer 125 and a transparent conducting layer 126. Theimage of the examined part is formed in the mosaic layer 123. The imagesensitive screen 122 is illuminated by the flying spot from the tube 16athrough the light transparent layer 126. The scanning illuminationchanges the conductivity of the layer 125 and converts thereby theelectrical pattern stored in layer 123 into successive electricalsignals corresponding to the image of the examined part. The electricalsignals are conducted to the receivers outside of the examined partwhere they are reconverted into visible images in the manner well knownin the television art. It should be understood that electrical signalsmay also be fed into different utilization circuits, such as using anabsorption negative, which are well known in nondestructive testing inindustry.

Another modification of the tube 16]) in which a photoconductivephotocathode is used instead of a photoemissive photocathode 34, isshown in FIGURE 1C. The tube 16C comprises only photocathode 34A whichmay be of described in FIGURE 1C may have a construction in which bothphotoemissive and photoconductive layers are used. Such a photocathodewill have a mosaic photoemissive layer on the side exposed to the imageforming radiation, a photoconductive layer, and a light transparentconducting layer on the side facing the source of scanning illumination.The image of the examined part is received by the mosaic layer and isconverted into a charge image. The scanning illumination converts saidstored charge image into successive electrical signals which are takenoff the conducting layer.

Another embodiment of the image sensitive pick-up element is shown inFIGURE 1D. In this embodiment the image sensitive element is not avacuum tube but a solid screen 127 which comprises two photoconductivelayers 125 and 125a and light transparent conducting layers 128 and 129,such as of cadmium, oxide, tin oxide, tin chloride or of noble metals,adjacent to the photoconductive layers on either side of the screen. Theimage of the examined part is projected on one side of said screen. 127and is converted into an electrical pattern of elec-- tricalconductivity changes in the layer 125. The flying light spot conductedby the light image conductor 114 is projected on the opposite side ofscreen 127, produces an increase of electrical conductivity of the layer125a, and converts thereby the electrical pattern in layer 125 intosuccessive electrical signals. The electrical signals are conducted tothe receivers outside of the examined part: and may be reproduced asvisible images in the manner well known in the television art. Inaddition, the electrical signals may be fed into various utilizationcircuits and. may actuate various devices as it is known in theindustrial sorting or testing of materials. In some cases it ispreferable to place a light opaque layer 125b between thephotoconductive layers 125 and 125a. Furthermore it is advisable toconnect the layers 125 and 125a to the terminals of a source of anelectrical potential to provide a. biasing field across said layers.Suitable photoconductive materials for layer 125 or 125a are selenidesas of sulphides of lead, cadmium or tellurium, oxides such as lead oxideor zinc oxide, antimonides, especially indium antimonide, and titaniumcompounds such as barium or lead titanates. It should be understood thatall these materials may be used as evaporated layers, sintered layers,mosaic layers, layers embedded in plastic, single crystals or a mosaicof crystals. The layers 128 and 125 may be continuous or in the form ofa mesh screen or a grid.

It should be understood that the relative position of the flying spotkinescope such as 16a and of the image sensitive member, such as 16b,16b, or 127 or any modifications thereof, may be reversed. This meansthat in some cases the flying spot kinescope instead of being situatedproximally in relation to the image sensitive member is now situateddistally in relation to the image sensitive member.

The housing 14 containing the television camera can be rotated in itsposition in the intrascope so that the optical system 15 can be made toface the window 18 or 18a and to see thereby various areas of thecircumference of the examined part. The rotation of the camera can beaccomplished by means of a pusher 15a which fits into extensions 10b ofthe box 14. The rotation of the camera may be preferable in some casesto the rotation of the whole intrascope which allows the accomplishmentof the same purpose.

The main rigid portion of the flexible intrascope is the televisioncamera 16. Therefore the shorter the television camera is, the easier itwill be for the intrascope to pass through sharply angulated or curvedpassages. One of the advantages of the novel pick-up tube 16 is that itmakes it possible to break up the smallest pick-up tube into twocomponent parts such as tubes 16a and 16b and intro duce each of saidtubes into the examined part separately, reducing thereby considerablythe rigid portion of the intrascope which is due to the televisioncamera, as shown in FIGURE 10.

To accomplish these objectives, the flexible intrascope 1a is introducedfirst into the examined part while containing only the box 5 housing thelight source 7. Inside of the intrascope 1a, proximally to the box 5,there is a ring-like partition which serves as a stop 27 for the pick-uptube 16/) which is to be introduced later. It is obvious that the shapeof this stop may vary. The rest of the intrascope 1a is empty. Theintrascope 1a is introduced first into the examined part. As the onlyrigid part in the intrascope is now the box 5, which is very small, thisintrascope can easily pass even through very narrow and curved passages.After the intrascope 111 has been introduced into the examined part fora desired distance, which can be read easily on the markings provided onthe outside wall of the intrascope, the next step begins. Now thehousing box 1417, in which the vacuum pick-up tube 16b is mounted, isintroduced into the intrascope. The housing box 1412 is pushed into theintrascope until it reaches the stop 27, which can be also ascertainedby the X-ray control. The box 14b may be held against the stop 27 byspring extensions 2711 on said stop 27. The housing box 14b may bepushed into its position by a flexible elastic guide 1501, which isfitted into the proximal end of the housing box 14a. For this purposethe housing box 14b is provided with a ring-like extension a at its baseas shown in FIGURE 10, which has spring-like properties. The head of theflexible pusher a fits into this extension and is kept in position byit. The flexible pusher 15a may also be provided with electrical coils6a at its distal end, which is adjacent to the element to be introducedinto the intrascope. The coils 6a are connected to the source ofelectrical power situated outside of the examined part. In this way thehead of the pusher may be given electromagnetic properties by closingthe circuit, energizing the said coils 6a. The pusher 15a will be held,therefore, in the elements to be introduced into the intrascope, such asboxes 14a, 1411 or the optical system 15, not only by the mechanicalpressure of the extensions 10a or 10b but by magnetic attraction aswell. When the pusher 15a is to be withdrawn, the current supplying thecoils 6a is shut ofl. To facilitate the guiding of the box 14b into theintrascope, a set of threads 86 may be used, which are at the endattached to the stop 27 and which are threaded through the perforationsin the extensions 87 of the house box 14b. After the box 14b has beenintroduced into its proper position, the intrascope, the pusher 15a, isremoved. Another set of threads 89 is attached to the extensions 88 inthe housing unit 14b and serves to pull out said box 14b to the exteriorof the examined part when the examination is finished. This arrangementis shown in FIGURE lb.

The housing box may be omitted in some cases and the tube 16b may beintroduced into the intrascope without any housing and will be held inposition by the same means as described above for holding the box 14b.

After the box 141) with the tube 16b has been introduced, the box 14ahousing the tube 16a is introduced now into the intrascope in a similarmanner as was described above. Both boxes 14b and 14a have openings attheir proximal and distal ends respectively, which makes it possible tobring the fluorescent screen 31 of the tube 16a in close opposition tothe photoemissive electrode 33 in the tube 16b. The boxes 14a and 14bare provided with mechanical means for securing a good contact of theproximal end of the tube 1611 with the distal end of the tube 16a. Oneway of providing such a contact is to make the compartment 14a fitinside of the spring-like flange 27a at the proximal end of thecompartment 14b. The housing box 14a contains vacuum tube 16a which hasbeen described above. The housing box 14a is provided with spring-likeextensions 10b which serve to accommodate the head of the pushing guide15a.

The housing box 14a is pushed into the intrascope until it reaches theposition of the stop 27b. This can also be checked by the X-ray control.The stop 27b is so situated that when the housing box 14a reaches it,the tubes 16a and 161) will be in apposition to each other. In somecases flexible coils, which can be converted into magnets by passingthrough them an alternating current from an outside source of electricalpower, may be provided on the stops 27 and 2712 or at extensions 10a or1012 of the intrascope to help the positioning of boxes- 14a and 14b. Inthis way the rigid portion of the intra scope, which has to pass througha narrow passage or acute curvature, is now only a fraction of the rigidpart of intrascopes, which use even the smallest pick-up tube ofconventional type. Thi represents an important improvement as it makesit possible to introduce the intrascope into parts which were notaccessible previously to examination. In case the size of the pick-uptube is not of critical importance, one of standard television tubes,after being miniaturized, may be used as well.

The size of the kinescope tube 16a may be reduced considerably if it canbe operated at a low voltage and produce at said low voltage sufficientillumination of the electrode 33. One way of accomplishing this purposeis disclosed in my US. Patent No. 2,586,391 which discloses amplifyingscreen consisting of a light reflecting layer, a fluorescent layer, alight transparent separating layer and a photoemissive layer. Saidscreen is disposed in the kinescope between the electron gun and thefluorescent image reproducing screen. The same objective may also beobtained by using between the electron gun and the image reproducingscreen a secondary electron emissive electrode, which may be of a solidtype or preferably of mesh screen, is of material having a highsecondary electron emission ratio, such as Ag:Mg or it may havedeposited on a mesh screen a layer of a highly electron emissivematerial, such as of CS0 or of Cash. As 6-10 electrons may be emitted bysaid screen for each incident electron, the voltage of the kinescope maybe considerably reduced. The electron-optical field between saidsecondary electron-emissive electrode and the fluorescent screen 31 willfocus the divergent secondary electrons into fine beams so that thedefinition of the image will not be markedly impaired.

There are certain drawbacks in the intrascope 1 or 1a described above.The separation of the fluorescent screen 31 from the photoemissiveelectrode 33 by the thickness of the wall of the vacuum tube 16a and ofthe tube 16b causes some unsharpness of the photoelectron beam 33a. Thisunsharpness is due to diffusion of light spot from fluorescent screen 31as it travels through distance equal to the thickness of the walls ofthe tubes 16a and 1611. By the time the light spot reaches thephotoemissive electrode 33, it has spread so that it cannot produce anymore a fine photoelectron beam. Besides the fluorescent light spotsuffers in the glass walls of the tubes 16a and 16b multiple internalreflections so that part of the fluorescent light will be scattered andwill strike different separated areas of the electrode 33 reducingthereby further definition and contrast. Furthermore, it is not alwayspossible to introduce component parts of intrascope separately as wasdescribed before. In some examinations, the time available is verylimited so that intrascope must be ready for the use as soon aspossible. In such cases, another modification of my invention is moresuitable. This embodiment 1b of the intrascope is shown in FIGURE 2. Inthis embodiment of invention, the tubes 16a and 16b are replaced by onevacuum tube having a composite target 19 described below. Thefluorescent layer 31b of phosphors described above is deposited on oneside of a very thin light transparent separating partition 19a, whereasthe photoemissive layer 3311 of one of the materials described above isdeposited on the opposite side of said partition. The partition 19a maybe of mica, glass, or of a suitable plastic and should preferably bevery thin, such as of the order of a fraction of millimeter in order notto impair definition of images produced by the said television pick-uptube. Better results may be obtained if the partition 19a is conductive.This may be accomplished by using for the partition a conductivematerial or by coating the partition on the side, which supports thephotoemissive layer, with a light transparent conducting layer, such asis known in the trade under the name of Nesa, indium compounds or ofcadmium compounds. In some cases the composite target 19 may bedeposited on the photocathode 34 instead of being supported by the sideWalls of said pick-up tube. In this event the separating layer 19a maypreferably be reduced to the thickness of a fraction of one micron.

The partition 19a may be placed in its position within the tube 16c bymeans of a metallic ring 98 having a flange 99 which supports thepartition, whereas the ring itself is attached to the walls of the tube.The crosssectional perspective view of the ring 98 and partition 19a isshown in FIGURES 2d and 2e. Instead of a metallic ring 98, thetransparent separating layer 19a, the fluorescent layer 31 andphotoemissive layer 3312 may also be supported by the mesh screen ofconducting or insulating material 82 as shown in the pickup tube 16d and16e and 16e illustrated in FIGURES 2a, 2b and 2c. Instead of a meshscreen a supporting layer of continuous type may be used and may be madeof one of the materials used for the separating layer 19a which areeither light transparent or electron transparent. In some cases it ispreferable to make the fluorescent layer 31b and the photoemissive layer33b of semispherical curved shape. In some cases the separatingpartition 19a may be omitted and the fluorescent layer 31b andphotoemissive electrode 33!] are both supported by the mesh screen 82 orby supporting element of continuous type 19a without any separatinglayer. This arrangement is possible only in cases in which thephotoemissive layer 33b and fluorescent layer 311) do not inactivateeach other and the photoemissive layer 33/] is conductive. The otherelements of the novel pickup tubes 16c, 16d and 162 are the same asdescribed above. At one end of the tube 160 there is disposed anelectron gun 28 which produces an electron beam 29. The electron beam 29is focused by electrostatic field 30 and is deflected by electrostaticplates 30a and 30b in two perpendicular to each other planes. Theelectrostatic plates are energized by signals from saw-tooth generators32 which are situated outside of the examined part. The generators 32are connected with electrostatic plates 30a and 30b by means of flexiblewires. In this way the electron beam 29 is made to scan the fluorescentlayer 31a of the composite target 19 in a regular television raster. Thefluorescent layer 31b may also be provided with an electron transparentmetallic conducting backing layer 310 such as of aluminum. Thefluorescent scanning light spot produces a scanning photoelectron beamfrom the photoemissive electrode 33h which may be of CsOAg or ofcaesium, lithium or rubidium on antimony, arsenic or bismuth. At theopposite end of the vacuum tube 160 there is provided photocathode 34which consists of a light transparent signal plate 34a, a lighttransparent insulating layer 3412 and of a photoemissive mosaic 340. Thesignal plate 34a may be a thin transparent layer of metal or otherconducting material. The insulating layer 34b may be of mica or othertransparent dielectric material and photoemissive mosaic 34C may be ofCsOAg or of caesium, rubidium or lithium on anti mony, arsenic orbismuth, as was described above.

In some cases it is preferable to focus the scanning electron beam 33aon the photocathode 34. The focusing has to be done by means ofelectrostatic field 30a. In such event the photocathode 34 or itsphotoemissive mosaic 340 should be preferably of curved semi-sphericalshape. The rest of the operation of the intrascope 1b using thetelevision camera 16c is the same as was described above. A considerableimprovement in definition of reproduced images may be achieved by makingthe fluorescent screen 31 of grainless phosphors.

The housing box may be omitted in some cases and the television tube maybe introduced into the intrascope without any housing and will be heldthen in position by the same means as were described above for holdingthe housing box.

In some cases the part to be examined is too small or too curved toaccommodate even the television camera 16. For example the introduclionof the intrascope 1a through narrow passages may be in some casesaccomplished because of separate two-step insertion of the tubes 16a and16b, but their subsequent assembling together in side of the intrascopeproves to be impossible because of the lack of suflicient space. In suchcases, it may be neces' sary to keep the tubes 16a and 16b apart fromeach other and to use an optical system 15c to focus the scanningillumination produced by the tube 16a on the photoemissive electrode 33in the tube 1611, as shown in intrascope 10, illustrated in FIGURE 3.

In some cases the optical system 150 may be housed in the compartment141;. In other cases it may be placed preferably in compartment 14a. Itmust be added that the use of the optical system 15c makes it necessaryto increase the output of light from the fluorescent screen 31, as only2% of the light will now reach the photoemissive electrode 33. The restof the operation of the intrascope 1c is the same as was described abovefor the intrascope 1 or 1a.

This arrangement will be. useful in locations which are known in advanceas not to cause any bending of the intrascope in the area between saidtubes 16a and 16/). It may be also of value in the examination of partswhere the degree of such angulation between the tubes 16a and 16b isknown in advance so that it may be overcome by the choice of a suitableoptical system.

In order to reduce pin-cushiOn distortion inherent in electrostaticdeflection system used in cameras described above and illustrated inFIGURES 1 to 3, I make the fluorescent screen of a semi-spherical shape.Furthermore, the photoemissive electrode 33 may be preferably alsoshaped semi-spherically to reduce further pincushion effects. Inaddition the photocathode 34 of the pick-up tube may also preferablyhave a curved semi-spherical shape which will help overcome furtherdistortion due to electrostatic focusing field 30a. The use incombination of a curved fluorescent screen 31 and of a curvedphotocathode 34 represents an important improvement of my camera overdevices of the prior art. The definition of the flying light spot may beconsiderably improved by depositing screen 31 on a supporting meshscreen 83 which was described above, instead of on the wall of the tube16.

In case extremely bright images have to be investigated the photocathode34 of the pick-up tubes described above may be provided with a layer ofphosphor on the side facing said image, which converts the. radiation ofstrong intensity into a fluorescence or phosphorescence of weakintensity, so that the pick-up tube will not be damaged by excessiveillumination. Such phosphors are well known in the art. Therefore it isbelieved that their description is not necessary.

In some cases it is preferable to reduce further the rigid part of theintrascope by providing the source of image forming radiation outside ofthe intrascope. This embodiment of my invention is shown in FIGURE 5.

The photocathode of the pickup tube 16b may also be made to provide apanoramic view of the examined part. The photocathode 34a in thismodification extends in a curved semi-spherical manner to the side wallsof the pick-up tube, as shown in FIGURE 5. One window 12a in thismodification is preferably situated at the end of the intrascope.

The novel intrascope 1 or 10 may be further simplified as shown inFIGURE 4. In this embodiment of my invention only one novel pick-up tube16] is used. The pick-up tube 16f has a photoemissive photocathode 34gwhich consists of a layer 34a transparent to image forming radiation, adielectric layer 341), also transparent to the image forming radiation,and photoemissive/mosaic 340. In a close spacing from the photocathode34g, such as not exceeding 0.25 millimeter but preferably much smaller,there is disposed a fluorescent screen 346. The screen 34a may besupported by a light transparent supporting layer such as of mica or maybe supported by a mesh screen 82 as was described above. The fluorescentscreen 34:: may be in some cases provided with an electron transparentlight reflecting conducting layer 34f on the side facing the electrongun 28. In some cases, said fluorescent layer 34e and backing layer 34]may be deposited on the photoemissive mosaic 34c, as shown in FIGURE 4.In such event a light transparent separating layer 3411 may bepreferably interposed between said photoemissive and fluorescent layers.At the other end of the tube there is disposed an electron gun 28 whichproduces an electron beam 29 for scanning said fluorescent layer 34g intelevision raster. The image of the examined part is projected on saidcomposite photoca hode 34g and produces a charge image in thephotoemissive mosaic 340, which has the pattern of said projected image.The scanning electron beam produces scanning light spot in thefluorescent layer 34e. The light spot scans the adjacent photoemissivelayer 340. The impingement of the light spot causes photoemissio-n ofelectrons which is modulated by the charge image established in themosaic 34c by the projected previously image of the examined part. Thesignals produced by the scanning light spot appear at the signal plate34a and can be converted over suitable resistor into video signals inthe manner well known in the television art. The light transparentseparating layer 34d is necessary to prevent detrimental chemicalinteraction between the photoemissive layer 34c and fluorescent layer342. In order to preserve sharpness of the scanning light spot, saidseparating layer must not exceed 0.15 millimeter in thickness. The layer34d may be dielectric, such as of mica, non-conductive glass orplastics. In some cases it is preferable to use a conductive layer andin such event the separating layer may be of glass, mica, plasticscoated with the material known as Nesa manufactured by Pittsburgh PlateGlass Company. It may also be made of tin salts, such as halides oroxides, cadmium salts or metal powders, such as of silver. In some casesit is preferable to make the separating layer of the two layers adjacentto each other, one of them being an insulating or semi-conducting layer,another one being a conducting layer. It is obvious that the compositephotocathode 34g may be deposited on the wall of the vacuum tube or maybe held by supporting means within the vacuum tube independently of theend walls of said tube. Such supporting means may be either in the formof mesh screen or of a continuous element which were both describedabove. The fluorescent layer 34e must be of phosphors having a veryshort persistence, such as of the order of 1 micro-second, which weredescribed above. The electron transparent layer 34 serves to improveefficiency of the light output from the fluorescent layer 342 and may beof aluminum. In some cases it may be omitted.

This system may also be used in the way shown in the intrascope 1a whichhas optical system between pick-up tube 16a and tube 16b and it is shownin FIGURE 4w. In such case the novel pick-up tube 1611 has the mosaicphotocathode 34 described above but the electrode 33 is eliminated; seeFIGURE 4a. The scanning of charge image produced on the photoemissivemosaic 34c is accomplished by the fluorescent light spot from the tube16a which is projected on the mosaic 340 by lens 15c. The impingement ofthe flying light spot which scans the photocathode 34 in televisionraster produces photomission from the layer 340, which is modulated bycharge image present thereon. As a result successive electrical signalsare formed which can be taken off the signal plate 34a and can beconverted into video signals in the manner well known in the art.

This novel television camera can also be used by placing the novel tube16b in close apposition to the tube 16a; see FIGURE 41). I

The fluorescent screen 34:: if made of a curved semispherical shape willhelp to reduce pin-cushion distortion inherent in electrostaticdeflection system. In addition the photocathode of the pick-up tube 16bmay also preferably have a curved semi-spherical shape which will helpovercome further distortion due to electrostatic scanning. The use incombination of a curved fluorescent screen and of a curved photocathoderepresents an important improvement of my camera.

The intrascope illustrated in FIGURES 4, 4a and 4b may also besimplified by providing the source of image forming radiation outside ofthe intrascope as was explained above.

In case a true color image of the examined part is wanted, a rotatingcolor wheel 50, drum, or truncated cone, composed of plural, e.g., threeprimary chromatic filters 51, 52 and 53, is placed before the televisionpick-. up tube 16b; see FIGURE 6. A similar wheel 50a rotatingsynchronously with the first color wheel 50 is placed in front of thepicture tube 37 in the receiver. Each examined field is scanned andreproduced in succession through a different primary color in the filterwheel. Therefore, three colored images, red, yellow and blue areprojected on the final viewing screen 56 in A second. The persistance ofvision lasts longer than of a second. Therefore, these three colorimages fuse in the mind of the observer and a multi-colored reproduction57 corresponding to the true colors of the examined part results. Thecolor wheels 50 and 50a are driven by induction motor located outside ofthe examined part, synchronized by synchronization stage which comparesthe incoming pulses with locally generated ones and thereby controls thespeed and the phase of the disc. Since the color wheels synchronizationis obtained from the video wave form, the phasing of the color filtersis automatically selected, that is, a given color automatically appearsbefore the receiver tube when that color is present before the pickuptube, as it is well known in television art. The motor may also belocated in the examined part.

The illuminating system 5 in this modification of the intrascope is thesame as described above and shown in FIGURE 1. The mounting of theilluminating system also may be the same as shown in FIGURE 1. Theoptical system 15 is essentially the same as described above and shownin FIGURE 1. In some cases additional lenses may be used between therotating wheel 50 and the television pick-tube 16b, 16 or any otherpick-up tube described above for a better focusing of the image of theexamined part on the photocathode of the pick-up tube. The mounting ofthe optical system may be the same as shown in FIGURE 1. The rotatingcolor wheel 50 in front of the television pick-up tube has threesections of colored glass corresponding to three basic chromatic valuessuch as red 51, blue 52 and yellow 53, and may be mounted on the bracket59. The rotating wheel is activated by the synchronous motor situatedoutside of the examined part and connected to the Wheel by means of theflexible insulated cable.

The image of the examined part is projected by the optical system ontothe photocathode of the television pick-up tube through the rotatingmulticolor wheel 50 and is converted by said television pick-up tubeinto video signals having the pattern of the examined part in the sameway as was explained above. The video signals are transmitted by theflexible co-axial cable to the amplifier outside of the examined part.The am lified video signals are conducted by the coaxial cable to theviewing tube 37 of the kinescope type. The video signals modulate thescanning beam 60 of the kinescope 37. The modulated scanning beam in thekinescope striking the fluorescent screen 61 of the kinescope isreproducing the images of the examined part. These images are projectedthrou h the color wheel 50a rotating synchronously with the similarcolor wheel 50 in front of the pick-up tube. In this way three coloredimages of the examined part are projected on the final screen 56 in A ofa second, blending thereby into one multicolored image due topersistence of the vision of the observer. The resulting multicoloredimages 57 can be visually examined on the screen 56 or may be recorded.It is obvious that with all intrascopes described above this colorsystem may be used.

Instead of a rotating color disc or drum the color images may beproduced by using sequentially three sources of illumination, such as asource of red light, a source of yellow light and a source of bluelight. First the red light, for example, is flashed on the examinedobject and the red image is produced thereby and is transmitted toreceivers. Next the yellow light is flashed on and the yellow image isproduced and transmitted to receivers. Next the blue light is flashed onthe examined object and the blue image is produced and transmitted toreceivers. If the red, yellow and blue images are all produced in ,6, ofa second, they will blend in Examiners eye into a multicolor imagewithout the use of any rotating color filters.

In some cases the use of the rotating color disc, drum or truncated conemay not be convenient and a system using a stationary color filter maybe preferable. It is obvious that the rotating color disc may bereplaced by stationary color filters such as dichroic mirrors, but insuch case two or three pick-up tubes must be provided in the intrascope.It is to be understood that all such color television systems come alsowithin the scope of my invention. In order to use a stationary colorfilter with one pick-up tube only it is necessary to split the image bysuitable optical means into plural, e.g., two or three images and toproject said split images through the stationary color filter onseparate areas of the photocathode. This embodiment of my invention isshown in FIGURE '7. The image 64 of the examined part is projected bylens 65 between two mirrors 66 and 67. The mirrors are parallel to eachother and equidistant from the optical axis. The mirrors produce fromthe original image 64 multiple secondary images such as 64a, 64b, 64c,etc. The lens 65a projects the image 64 and the secondary image 64a and64b on the different areas A, B and C of the photocathode 68 of thepick-up tube, which may be of any type described above. There are manyoptical systems for splitting the image of the examined part into pluralsymmetrical images, which are well known in the art; see U.S. PatentsNos. 2,389,646 and 2,465,652, and it is to be understood that thedescription of such an optical system used in my intrascope should beconsidered only in an illustrative and not in a limiting way.

Each photocathode 68 has signal plate 69, dielectric layer 70 andphotoemissive mosaic layer 71, as was described above. Three symmetricalimages are projected on different areas, A, B and C of the photocathodewithout overlapping each other. The stationary color filter havingplural elements, such as the red one 67, the yellow one 67a, and theblue one 67b, are provided outside of the pick-up tube in cooperativerelation with said three different areas A, B and C of the photocathodefor receiving the original image 64 and symmetrical images 64a and 64b.The filters may also be positioned inside of the pickup tube in front ofthe photocathode. Therefore the image 64a which passes through the redfilter 67 will produce in the area A image 64a having red information.The image 64 which passes through the yellow filter 67a will produce inthe area B image 64 providing yellow information, and the image 64bproduced by the filter 67b will form in area C image 61b, which providesblue information. The scanning electron beam 33a produced by the flyingspot light, as explained above, scans these images on the photocathodeand produces video sigrals having the pattern of said red, yellow andblue images. When the area A of the photocathode is scanned videosignals are produced which after amplification and improvement of theircontrast are fed into red" kinescope. Next the electron beam 33a scansthe area B and image 64' and converts said image into video signals.These video signals correspond to the yellow image 64 and are fed intoyellow kinescope. In the same Way the video signals corresponding to theblue image 64b are fed into the blue kinescope. It is obvious thatinstead of multiple kinescopes a single tricolor kinescope may be usedas welL It is also evident that the scanning of the charge images on thephotocathode does not have to proceed systematically from the area A toarea B but also may be completely interlaced. The basic feature of allthese arrangements is that video Signals derived from the scanning ofthe area A of the photocathode have to be fed into red channel, thesignals produced by scanning area B of the photocathode have to be fedinto yellow channel and signals from area C should be fed into bluechannel.

It is obvious that there are many systems which can produce pluralnon-overlapping images and it is to be understood that all such systemscome within the scope of this invention. It is also obvious that opticalmeans or filters may be used to split not the whole image simultaneouslyinto plural symmetrical images but to split each line of the image intothree non-overlapping line images. These line images may be projectedthrough multicolor filter to produce non-overlapping color line images.Each of said lines will then be scanned and converted into red, yellowand blue video signals, as was ex plained above.

The television camera of the type shown in FIGS. 4, 4a and 4b can alsobe used in this novel color television intrascope. FIG. 7a shows the useof the pick-up tube 16g for producing color images. It is obvious thatthe same system may be used with pick-up tubes 16b or 16b The novelpick-up tube 16g has a mosaic photocathode 76 which consists of a lighttransparent conductin layer 76a, light transparent dielectric layer 76band of photoemissive mosaic layer 76C. The above mentioned layers may beof the materials described above. The photocathode 76 may be dividedinto plural areas such as three independent from each otherphotocathodes, as was shown in FIG. 7. This may be accomplished also bythe insulating means which extend from the conducting layer 76a intophotoemissive layer 76c. In another modification instead of this pluralphotocathode, three independent photocathodes may be deposited on thewalls of the pick-up tube or may be mounted in the inside of saidpick-up tube in such a manner that the edges of said photocathodes donot come in contact with each other. In the preferred form of thissystem, the optical projection of split images is of such a manner thatsaid images do not overlap each other on the photocathode but fall inthree separate areas A, B and C. In such case, only the signal plate 76ahas to be divided into three different areas such as 76A, 76B and 76Cwhich are insulated from each other or are noncontiguous to each other.In order to be able to transmit red video signals only to the redchannel, yellow video signals only to the yellow channel and blue videosignals only to the blue channel in this modification, the photoemissivemosaic 76c and its dielectric layer 76b do not have to be split any moreinto independent non-contiguous units. By the use of one of the opticalsystems described above, the image of the examined part is split intothree separate images which are projected on three separate areas 76A,76B and 76C. Each of the conducting signal plates of said photocathodesis connected to its own color channel only. In this way the signals fromthe signal plate 76A will be, for example, directed to the redkinescope, the signals from the signal plate 768 to the yellow kinescopeand signals from the signal plate 76C will be fed into the bluekinescope.

Another way to produce color images is to subject various areas A, B andC of the photocathode or the scanning beam to modulation by signals ofdifferent frequencies from an outside generator and by making eachprimary color channel responsive only to one frequency which is madearbitrarily representative of said primary color. In this way the red,yellow and blue images will be fed into red, yellow and blue channelsresp ctively by means of appropriate filters or decoders. Thisarrangement allows the use of one signal plate instead of three signalplates in the systems described above.

My invention is not limited to visible light images. It should beunderstood that my intrascope may be made responsive to invisible imageson either side of visible spectrum by using appropriate photosensitivelayer in the photocathode of the television camera. It is to beunderstood also that my intrascope may serve for receiving images formednot only by various electromagnetic radiations, such as ultraviolet,infrared, etc., but also by particles radiation such as neutrons, alphaparticles, protons, electrons or by ions, In such case, the photocathodeof the pick-up tube described above may be provided with an atomicparticle sensitive phosphor on the side facing said image or may have aspecial electron or other atomic particles emissive photocathode.

FIGURE 8 shows a pick-up tube 16h having atomic particles sensitivephotocathode which is responsive to an atomic particles image and emitssecondary atomic particles having the pattern of said image. It is to beunderstood that the photocathode 77 is shown only for illustration asthere are many types of photocathodes sensitive to atomic particles, asevidenced by my above mentioned patents. The target 78 is scanned by aslow electron beam 33a from the electrode 33 in the manner describedabove. The electrons of the scanning beam 33a are deposited on thedielectric layer 79 of the target and are stored there. At the time ofimpingement of the beam of gamma rays or of atomic particles from thephotocathode 77, the dielectric layer 79 becomes conductive. Theelectrons of the scanning beam 33a can now pass through the dielectriclayer 79 to the signal plate 80 and produce video signals. In some casesthe photocathode 77 may be in apposition with the target 78.

The above described type of pick-up tube may also operate using a fastscanning electron beam instead of a slow beam. This modification ispreferable in cases in which the particles emitted by the photocathode77 have small velocity, for example, in case of a photoemissive cathode.In such case the signal plate 80 should be on the side of the target 79which faces the scanning electrode 33. The rest of the operation of thisintrascope may be the same as described above.

The storage target may also be of the composite type and may consist ofa fluorescent light reflecting layer 81, a fluoroescent layer 81a, alight transparent dielectric layer 81b, such as of mica, glass orsilica, and a photoemissive mosaic layer 81a, as shown in FIG. 8a. Insome cases the photocathode 77 and the composite storage target 83 maybe in apposition to each other, which means contiguous to each other. Insome applications the storage target 83 may also be used instead of thephotocathode 77 and will serve to receive an image of invisibleradiation and to convert said image into a charge image. Also the target78 may serve as a photocathode; see FIG. 8b.

Furthermore, my intrascope may serve for investigating images producedby supersonic radiation. In such case, the photocathode of the pick-uptubes described above is replaced by the supersonic sensitivephotocathode, for example, of quartz, compounds of titanium, such asbarium titanate or lead titanate, or Rochelle Salt or ADP. Theintrascope must have at its distal end a membrane and must also have amedium to transmit supersonic vibrations to pick-up tube. Instead of amembrane, the endwall of pick-up tube may form the end of intrascope andwill then receive supersonic image directly.

When using an invisible radiation for producing an image of the examinedpart, the color reproduction of said image may also be obtained, as itis explained in my US. Patent No. 2,593,925. Another system for colorreproduction of invisible radiation images is to make separatesub-photocathodes A, B and C, as described above, selectively sensitiveto different groups of frequencies present in said invisible radiationimage. For example, sub-photocathode A may be made to receive radiationonly of wavelength 3-4000 A. either by means of a special selectivefilter in front of said sub-photocathode or by making the photosensitivesurface selectively responsive only to said wavelength. In the samemanner the sub-photocathode B will receive only radiation of 1000-2000A. It is obvious that the wavelengths quoted above should be consideredonly in an illustrative and not in a limiting sense. In the same mannerradiation on the far end of the spectrum may be arbitrarily divided invarious groups of frequencies. By assigning arbitrarily three colorchannels, such as red, yellow and blue to said three sub-photocathodes,a multicolor reproduction of an invisible image may be obtained. Also,the rotating color disc .Or drum which is provided instead of visiblecolor filters with filters selective for various frequencies present inthe invisible image may be used for the same purpose. This modificationwill then allow the use of only one photocathode instead of threesub-photocathodes.

In many cases it is preferable to have the source of invisible light orof other image forming radiation used for examination independent of myintrascope and outside of the intrascope. In such arrangement the sourceof image forming radiation may be introduced prior to or subsequent tointroduction of the intrascope into the examined part. This embodimentof my invention will facilitate the insertion of the intrascope as itwill reduce the size of its rigid parts.

The novel television cameras described above both for invisible andvisible image forming radiation operate by means of the photoemissiveeffect or by means of bombardment induced conductivity effect. It shouldbe understood, however, that similar television cameras which may use aphotoconductive or photovoltaic effect instead of a photoemissiveeffect, described above, come also within the scope of my invention.

It is evident that all intrascope used for receiving images or signalsof ionizing radiations, such as gamma rays, electrons, neutrons,protons, etc. may serve to reproduce images without having any opticalsystem. In such case the window of the intrascope is preferably situatedat the distal end of the intrascope, as shown in FIGS. 5 and 6.

All the intrascopes described above may be further reduced in size byomitting the encasing and holding member 26, as shown in FIG. 5a. Inthis modification of my invention, the television pickup tube may be ofany of the types described above. The television pick-up tube may beinserted into the examined part by means of a flexible or semi-flexiblepushing guide 15a, according to the type of the examined object. Thetelevision camera, e.g., 16e, is placed in a housing compartment 92which is provided at its proximal end with extensions 94 for receivingthe head of the guide 15a. At the other end of the housing compartmentan extension is provided for the optical system 93. In some cases asemi-flexible transparent tip or a tip having window 91 therein may beprovided at the end of the housing 92. In some cases additional windowswith lenses may preferably be added in the side walls of the housing box92. In such event the photocathode of the pick-up tube 16e shouldpreferable be of a panoramic type, as was shown in FIG- URE 5.

The intrascopes of the type described above may be further simplified byomitting ,the housing box 92 and introducing television pick-up "tubeinto the examined part without any protective compartment. In such casean extension or a socket are provided at the proximal end of thetelevision camera to accommodate the head of the guide 15a. Anotherextension is provided at the distal end of the television pick-up tubeto support the optical system 93.

In this modification of my intrascope the head of the pushing guide 15amay be fitted into extension at the proximal end of the camera tube inthe same manner as was described above for fitting the guide 15a intoextensions in the housing compartment. The pushing guide may also bescrewed onto the socket mounted at the proximal end of the pick-up tube.Also, electromagnetic coils described above may preferably be used inthis modification of my invention to secure a good contact.

In some applications it may be desirable to remove the guide a from thecamera tube after its insertion. In such case the camera is providedwith the threads 89 described above to pull out said tube afterexamination is concluded. In some applications the pick-up tube may beencased in an inflatable transparent sheath which is inflated after theinsertion of intrascope.

It is obvious that all those simplified intrascopes described above mayalso be used for producing color images of the examined part in themanner described above. It is also to be understood that thesesimplified intrascopes may be used in combination with a source of aninvisible radiation either of corpuscular or of undulant type.Furthermore, it is to be understood that the simplified intrascope mayuse pick-up devices based on the photoconductive or photovoltaic effectinstead of the photoemissive' effect described above.

For producing color images in some cases instead of separate signalplates, a circuit having keying amplifiers may be used as well. Thiscircuit activates amplifiers for video signals in a predetermined timesequence so that the signals coming from the area A and representing redsignals are amplified by amplifiers, whereas signals from the yellowarea B and blue area C are not amplified and therefore are notreproduced. Next when the yellow area B is scanned, the amplifiersreceiving yellow signals are activated by said keying circuits, whereasamplifiers for red and blue signals are kept inactive. The keyingamplifiers are well known in the art. It is believed, therefore, thattheir detailed description would only serve to complicate the drawings.In some cases, equalizing circuits should be provided in addition, inorder to equalize differences in signals caused by different exposuretime of the area A, B and C to the image forming radiation.

It should be understood that the relative position of the flying spotkinescope, such as 16a, 112 or 109, and of the image sensitive member,such as shown in FIG. 1 or in FIG. 4a, or in FIG. 8, or in anymodifications of the invention described in specification may bereversed. This means that in some cases the flying spot kinescope,instead of being situated proximally in relation to the image sensitivemember is now situated distally in relation to the image sensitivemember. It should be understood that such modification of the positionof the elements of the endoscope comes within the scope of my invention.

In some examinations the television endoscope or intrascopes describedabove are still too bulky to be introduced into narrow passages orcavities. For such cases I devised a novel intrascope in which one orall of the vacuum tubes used in the intrascopes, such as televisionpick-up tube or image-sensitive tube or flying spot tube, also known asa kinescope tube, are constructed in such a manner that all of theirsidewalls or a part of their sidewalls or their endwalls are flexible toconform to the tortuous configuration of the passages.

Reference is now made to FIGURE 9, which illustrates one of theembodiments of this invention. In this embodiment the novel flying spotkinescope 85 has flexible portions-86 and 87 in the sidewalls 88. Thetube 85 has section A which houses the electron gun 90 and which is of arigid material, such as glass, metal or a ceramic. Also the section Bwhich houses two pairs of deflection plates b and 30b is of rigidmaterial, such as glass, metal or ceramic. The endwalls 93 and 93a mayalso be of rigid material, such as glass, metal or ceramic. Thefluorescent screen 94 with a metallic electron pervious backing layer 95are deposited on the endwall 93. In some cases the backing layer 95,preferably may be omitted. Between the section A and the section B, thesidewall 88 has the flexible section 87 Between the section B and theendwall 93 is mounted another flexible section 86. The sections 86 and87 are made of a flexible material which has malleability to conform toconfiguration of examined part. I found that the flexible sections 86and 87 may be made of a plastic material, such as of one offluorocarbons. In particular, I found that tetrafluoroethylene or itsderivatives, such as Teflon made by Du Pont Company of Wilmington, Del.,are suitable for this purpose. I also found that polyesters, such asMylar or Cronar manufactured by Du Pont Company of Wilmington, Del., maybe used for this purpose. In addition, silicone plastics, such asiSilastic, made by Dow- Corning and isocyanate plastics, such asEccosorb AN made by Emerson and Cumming, may be useful. I discoveredthat these plastic materials with the exception of tetra-fluoroethylene,are slightly pervious to the air and as a result they do not maintainwell vacuum in the tubes. I found, however, that this difficulty couldbe overcome by metallizlng, such plastic materials, with a thin layer ofaluminum or other metals. This metallization will not impair theflexible nature of the above described materials. It should be addedthat ordinary rubbers proved to be unsatisfactory for this purpose.

The flexible sections 86 and 87 are fused to the adjacent rigid parts bymeans of Kovar seals or by bending them with heat resistant glues, suchas Ardalit, manufactured by Ciba Company, or preferably with Du Pontfabrics and finishes Departments adhesives 4684 and 4695. When using4695 to adhere a polyester, such as Mylar" to the glass, the adhesiveshould be coated on polyester, solvents evaporated, then combined withglass at 350 F. followed sometimes by an additional 10 minutes curing at350 F. When adhering polyesters to a metal, such as aluminum, copper,brass or steel, the above described procedure may be followed as well.The resulting bond was found to withstand flexion well. The presence offlexible sections 86 and 87 will allow the vacuum tube to conform toconfiguration of the passages through which the endoscope has to pass toenter the examined part. In many examinations, especially in the humanbody, the main difliculty resides in constricted passages which lead tothe examined organ. For example, the stomach has ample room toaccommodate the endoscope, but the esophagus at the junction with thestomach forms a sharp anterior angulation which has a small diameter andwhich can accommodate only a small rigid object. The rigid part of thetube is now only the electron gun which can be made small enough for thepassage through the esophagus or other narrow passages. The only otherrigid parts of the tube 85 are the deflecting plates 30a and 30b, whichare small per se and which, furthermore, being separated from theelectron gun by the flexible part 87 of the tube do not contribute anymore to the length of the rigid portion of the tube.

The novel endoscope 84, shown in FIG. 10 is provided with a vacuum tubehaving flexible walls 86 and 87 will now be able to pass in all patientsthrough the esophagus into the stomach, as such a vacuum tube used in mydevice will be able to conform to the shape of the esophagus.

The tube 85, after the passage through the esophagus or any othersimilar narrow passages, will be distorted in shape and will, therefore,not be able to function. For example, the electron beam from theelectron gun 90 may now be directed to the sidewall 88 of the tubeinstead of to the fluorescent screen 94, as shown in FIG. 9a in order toreestablish the original shape of the vacuum tube, which is essentialfor its operation, I use two flexible conduits 96 and 97, which areattached to the sidewalls of the vacuum tube and to the distal endwalls93 of said vacuum tube. In some cases they should be attached also torigid section B. The conduits 96 and 97 may be of flexible materials,such as were described above, The conduits 96 and 97 extend beyond thevacuum tube to the outside of the examined part and are connected to asource 98 of compressed air, oxygen or liquid. This source 98 isdisposed outside of the examined part. When the endoscope is in thelocation in which there is enough space for vacuum tube to reestablishits normal configuration, the valve 99 which controls the passage of theair is opened and the pressure of the compressed air will causestraightening of the bent tube 85. Instead of the air or oxygen also afluid underpressure may be used as well. The use of pneumatic orhydraulic means to reestablish the proper configuration of the vacuumtube represents an important feature of my invention as otherwise thewhole endoscope would fail to p erate. The conduits 96 and 97 are inaddition provided with a valve 100 controlled openings at the distal andto provide insufflation of air or liquid into examined cavity as it maybe necessary in some examinations. The valve 100 serves also as a safetyoutlet in case the return of fluid or air from the conduits 96 or 97should fail. In such an accident the endoscope could not be withdrawnfrom the patients body as the vacuum tube 88 would not be able to foldand to conform to the configuration of passages. By opening the valve100, the escape of fluid or air is provided which will reestablishflexibility and malleability of the vacuum tube 85.

In some cases in which the geometric configuration of the tube is notvery critical, instead of flexible conduits 96 and 97, used toreestablish the original shape of the tube, we may use flexible sections86 and 87 made of a resilient material, which will by itself revert tothe original form after the pressure by the walls of the passage isremoved. I found that materials, such as silicone rubbers, manufacturedby Dow-Corning Co. are suitable for this purpose.

I found that when using fluorocarbons as a plastic material for flexiblesections 86 and -87, a complication arises due to escape of negativefluorine ions during the baking of the tube. These negative ions cause afast deterioration of the fluorescent screen or of the photo cathode. Ifound that this difficulty could be solved by providing a flexibleconducting grid opposite the flexible sections 86 and 87 and which isconnected to the source of a positive electrical potential during thebaking of the tube and which intercepts the negative ions, .or bymetallizing the inner surface of plastic material by deposition of alayer of aluminum.

It should be added that the baking of the vacuum tubes having flexiblesections should be preferably done at temperatures below 150 C.

The flexible conduits in some cases may be preferably attached to lighttransparent extensions 100a mounted on the sides of the endwall of thevacuum tube instead of being attached directly to the endwall of thevacuum tube, as shown in FIGURE 9b.

In some cases it is preferable to make the whole sidewall 88a of thevacuum tube '85 flexible instead of having a combination of rigid andflexible sections as was described above. In such case the electron gunis mounted on the endwall 93a of the tube which is of rigid material.This construction is shown in FIGURE 90. In other cases it is necessaryto make the endwall of the tube of a flexible material or to insert aflexible section into said endwall. The flexible endwall may be used incombination with a flexible sidewall or with a rigid sidewall.

It should be furthermore understood that the flexible construction ofthe electron tubes applies also to nonvacuum tubes, such as gas tubes,like Geiger-Muller tubes, proportional counters, ionization chambers,etc.

In some cases the pressure source 98 should "be preferably locatedwithin the examined body or examined part. The pressure source 98 may belocated within the endoscope or outside of endoscope. In some cases,instead of pneumatic or hydraulic means, mechanical means, such assprings or telescoping rods may be used to reestablish the shape ofvacuum 85.

It should be furthermore understood that the novel construction of thevacuum tube described above applies not only to the kinescope type oftubes but also to all types of television pick-up tubes, one of which isillustrated in FIG. 11, or to all image sensitive vacuum tubes describedin this specification, some of which are illustrated in FIGS. 1, 1A, 1B,1C, 2a, 8b, etc.

The novel pick-up tube 110 may be of photoemissive type, photoconductivetype or photovoltaic type. Suitable materials for photoemissive photocathodes are CsOAg or CsSb or other metal alkali, such as K, Na or Rbwith Sb, As, or Bi.

Suitable photoconductive materials are selenium or its compounds,sulphides of lead, cadmium or tellurium, oxides such as lead oxide orzinc oxide, antimonides, especially indium antimonide. It should beunderstood that all these materials may be used as evaporated layers,sintered layers, mosaic layers, layers embedded in plastic, singlecrystals or a mosaic of crystals.

In addition, the television pick-up tube 110 may have an image sensitivescreen which combines both photoemissive and photoconductive layers. Thephotocathodes or screens 111 may be of continuous type or of mosaictype. The photocathodes or screens 111 may have a planar shape or may bepreferably of convex shape. The scanning electron beam may be of highvelocity type or of a low velocity type. In conclusion, it should beunderstood that all types of television pick-up tubes or of imagesensitive tubes come within the scope of this invention.

The novel endoscope 84 having flexible vacuum tube 85 is shown in FIG.10. It should be understood that the image sensitve element 16b or anyof its modifications described in this specification could beconstructed with partially or totally flexible sidewalls, as wasdescribed above. The remaining parts of the endoscope 84 may haveconstruction illustrated in FIGURES 1 to 8. The image sensitive memberand tube 85 may be in contact with each other.

The novel pick-up tube has the photocathode 111, the deflecting plates112 and 113 and the electron gun 117 for producing the scanning electronbeam and electrostatic focusing means 23, as is well known in thetelevision art. In addition the novel pick-up tube 110 has fiexiblesections 86 and 87 in the sidewalls which were described in detailabove. Besides the novel pick-up tube 110 has flexible conduits 96 and97 connected to an extraneous source of compressed gas or liquid, as wasdescribed above.

It should be understood that the novel pick-up tube 110 may have thewhole sidewall 88b made of a flexible material, as was described above,and as it is shown in FIG. 12. The use of a flexible television pick-uptube 110 in the endoscope may be in some cases preferable to the use ofa television system composed of two separate elements, as describedabove,

In another embodiment of invention, illustrated in FIG. 13, thekinescope 109 which produces the flying spot illumination of the imagesensitive member 120, which may have construction of tube 16b or 16B or16C, or of screen 127, or of any modifications thereof, is disposedoutside of the examined part and has, therefore, no limita tions anylonger as to its size or flexibility. The kinescope 109 has a similarconstruction as the flying spot kinescope 16a described above. It shouldbe understood, however, that it can be now of magnetic or electrostatictype as it is not limited any more as to size. The flying spot lightproduced by the electron beam 112 is projected by a suitable opticalsystem 113 on a flexible novel light conductor 114.

The image conductor 114 consists of multiple fibers of material having ahigh refractive index such as quartz, rutile or special plastics. Inmany applications the image conductor must be flexible and easilymalleable. In such cases, acrylic plastics, such as Lucite orpolysterenes may be used. Especially Lucite is suitable for this purposebecause it causes smaller losses of conducted light than othermaterials. Lucite and other above-mentioned materials characterized by ahigh refractive index have the property of internal reflection of thelight conducted by them. Such materials cannot conduct a whole image assuch but they can conduct well a light signal, which means an imagepoint. The size of the image point I found is determined by the diameterof a single conducting fiber 114A. In my image conductor I assembled abundle of such fibers which form a mosaic-like end-faces and which,therefore, can conduct plurality of image points. All these image pointswill reproduce at the other end-face of the image conductor the originalimage, pro vided that the ends of image conducting fibers remain intheir original spatial relationship. Each fiber 114A should have, as wasexplained above, a diameter corresponding to the size of one imagepoint. The diameter of 0.1 millimeter is well suitable for the purposesof my invention. In order to conduct an image of an area, e.g., of onesquare centimeter, we must have many fibers, the number of fibers beingdependent on the resolution of reproduced image that we desire. If theresolution of the conducted image should be four lines per millimeter,and if the image is of one square centimeter in size, we will need 40fibers of 0.25 millimeter in diameter. The light conducting fibersshould be polished on their external surface very exactly. Each of themmust also be coated with a very thin light opaque layer 114B to preventspreading of light from one fiber to another. I found that without saidlight-impervious coating, the image will be destroyed by leakage oflight from one tube to another. The light opaqued layer should have alower index of refraction than the light conducting fiber itself. Such acoating may have a thickness of only a few microns. I found a greatimprovement of flexibility of the light conductor 114 can be obtained byhaving the light conducting fibers 114A glued together only at theirend-faces 114a and 114k. This is a very important feature of my devicebecause the main requirement from the light conductor 114 is itsflexibility and malleability. If the fibers 114A are glued togetheralong their entire length, the flexibility and malleability is so muchreduced that it may not be possible to use it in many examinations inwhich the walls or passages are fragile and may be damaged by a rigidinstrument. [found unexpectedly that having the conducting fibers 114Afree along their path between the end-faces will not cause anydeterioration of the conducted image. I found that in spite of the factthat fibers between their end-surfaces were freely movable, there was noblurring of the conducted image. It must be understood, however, thatthe fibers 114A at both end-faces of the conductor 114 must rigidlymaintain their spatial relationship. Another important feature of thisconstruction is that the diameter of the light conductor 114 can be nowincreased because no space consuming hinder or flue is present betweenthe fibers 114A except at their end-faces. Instead of using the binderat the end-faces of fibers 114A, they may also be held together at theirend-faces by a fine mesh screen. Each fiber is threaded through oneopening of said mesh screen and is being held by said screen in constantposition. It may be added that smaller loss of light may be obtained ifthe fibers 114A are hollow inside instead of being solid.

The number of fibers that can be used in many examinations will belimited by the diameter of the passages through which my intrascope hasto pass. As in many situations, the channel may be only 1-2 cm. wide, itwill be impossible to use a great number of fibers or a singlerod of alarge diameter. I succeeded in overcoming this limitation by using incombination the light conductor 114 with a demagnifying optical system140. By the use of the demagnifying optical system I can reduce theexamined field to the diameter of the image conductor 114. If theoptical system will demagnify the image five times, I can examine thefield having 25 cm. with the image conductor having the diameter of only1 cm. This combination of a light conductor with an optical systemrepresents a very important feature of my invention, as it is not alwayspractical or feasible to limit the examined field only to the diameterof the image conductor.

The light image conductor 114 may be introduced into examined partsimultaneously with the intrascope. In some cases it is preferable tointroduce by intrascope first and then insert the image conductor intointrascope. In some cases the optical system 113 or may be attached tothe end-face 11412 of the image conductor to make one unit.

In some cases it is possible to use a light conductor 114- (whichconsists of a single large rod instead of plural fibers 114A) as wasdescribed above. The material for the single rod conductor may beflexible acrylic plastics, polysterenes or Lucite. The light conductingrod must be coated with a light-impervious layer 1148 of material havinga lower index of refraction than the rod itself, such as carbon,graphite or aluminum, except on the surfaces which serve to admit thelight or to let the light escape from the conductor. The single rodconductor cannot conduct an image but only successive light signals.

The proximal end 114a of the light conductor 114 must be maintained in afixed spatial relationship with the flying spot kinescope 169 bymechanical means which may be constructed in the form of a perforatedrigid member 117. The light conductor 114 passes through the aperture ofsaid member and is attached thereto. The member 117 is rigidly attachedto the kinescope 109 and establishes thereby fixed relationship betweenthe proximal end 114 of conductor and the kinescope 109. The lightconductor 114 directs the successive light spots produced by the flyingspot kinescope into the endoscope 115. The scanning light spots emergingfrom the distal end 114b of the conductor 114 are focused by a suitableoptical system 113a on the image senstive member 120. The impingement ofscanning illumination converts the electrical pattern which representsthe image of the examined part and which is stored in said member 120into successive electrical signals. The electrical signals are conductedto the outside of the examined part by wires 43 or by printed circuitsand are fed into receivers to reproduce the image. In addition,electrical signals may be used to activate various circuits or devicesused for industrial sorting and testing. The distal end 114b of thelight conductor 114 must also be maintained in a fixed position inrelation to the image sensitive member 120, which may be of any typedescribed above, such as tube 16b or 16B or or screen 127, when theimage of the examined part is transmitted. The rigid plates or rods 116and 117 with rigid extensions 116a and 117a, to which the distal end114b of the light conductor is attached, serve to maintain the distalend of the light conductor in a fixed position. I found furthermore thatthe endoscope 102 will not operate properly if the distal end 114 of thelight conductor 114 and the image sensitive element 120 are notmaintained in a fixed position. The rigid rods 118 and 119 connected tothe image pickup element 120 serve for this purpose. It should beunderstood that instead of rods, a rigid box, which encloses both theelement 120 and the end 1141) of the conductor, will provide theirimmobilization as well. The remaining parts of the endoscope 102 may bethe same as described above.

It should be understood that the image sensitive element 120 may havemany embodiments, all of which come Within the scope of this invention.The pick-up element 120 may have flexible sidewalls, as was describedabove, in some sections or throughout the whole length of sidewalls.Furthermore, element 120 may have completely rigid sidewalls when usedin combination with a light conductor 114. The image pick-up element 120may be of photoemissive type or may be of photoconductive type ofphotovoltaic type and may comprise any material described above.

Another improvement of the endoscope is shown in FIG. 14. I found thatthe loss of light conducted by the conductor 114 becomes very high ifthe conductor extends over the length of a few feet. It is necessary,therefore, to utilize all the light available from the flying spotkinescope 109. The optical system 113 or.113a in the fastest form stillcauses a loss of at least 90% of useful light. I found, therefore, thatin examinations of remote parts, it was necessary to eliminate theoptical system 113 or 113a or both. FIG. 14 shows flying spot kinescope122, in which all of the endwall 111a or a part of said endwall isreplaced by the light conductor 114, which may be of materials describedabove, but preferably should be of quartz. The proximal end-face 114a ofthe conductor 114 may be flush with the rest of the endwall of thekinescope 122 or may extend inside of the kinescope 122. The fluorescentscreen 94 is deposited on said end-face 114a. This constructioneliminates the optical system and in spite of it, there is no loss ofsharpness of the scanning light spot, because of a close apposition ofthe fluorescent screen 94 and of the light conductor 114.

A similar construction is used in the distal end 11% of the conductorwhereby the distal end 114b enters into image sensitive member 120 toestablish an optical contact with the image sensitive screen, such as34, 34A, 34B or 111 disposed in said image sensitive member.

The same construction may be applied advantageously to the embodiment ofinvention shown in FIG. 1D whereby the distal end 114 of the lightconductor 114 will be in contact with the screen 127.

A rotating mirror 21a may be used in addition to lens 21 to receive theimage through various windows. The remaining parts of the endoscope 103may be the same as described above.

It should be understood that in examinations in which the definition ofthe image is not important, the image conductor 114 may be placed incontact with the endwall of the flying spot kinescope or with theendwall of the image sensitive member either of television type or ofimage reproducing type, without penetrating into such a vacuum tube orphotocell.

In another embodiment of invention the flying light spot tube is used toproduce a scanning illumination of the examined body instead of thescanning illumination of the image sensitive element, as was describedabove, and is disposed outside of the examined body. This endoscope 104is shown in FIG. 15. The kinescope 109a may be of any of constructionsdescribed above, such as the tube 16a, 109 or 122. The light conductor114 may be the same as was described above. The flying spot is projectedby the optical system 150 onto the examined part.

The optical system 150 is an important feature of this invention. As thediameter of the image conductor 114 is limited by the narrow passages,the field of the examined body, which may be scanned through the imageconductor, is necessarily limited. By using, however, an optical system150, which produces five-fold enlargement, it is possible now to coverthe field of the examined part, which is five times largenThis featureproved to be very important in some examinations.

The reflected light spot is admitted through the window 18 to the imagesensitive element 131, which in this construction may be in the form ofa multiplier phototube. In some cases the solid state photoconductivedevices, such as photodiodes or phototransistors, may be used as animage sensitive element instead of a vacuum tube 131. It should beunderstood that the multiplier phototubes, such as 131, photodiodes orphotocells, such as 127, cannot produce an image without the use of ascanning illumination for forming plurality of successive image points.The use of an ordinary field illumination in combination with phototubesor photocells will produce only signals but not images.

The reflected successive light spots are converted by the element 131into successive electrical signals. Electrical signals are conductedoutside of the examined part and may be reconverted into visible images,as is well known in television art. It should be understood that theelectrical signals may be also fed into various utilization circuitsprovided with absorption negatives or other mechanism used for sortingand testing materials. I found that an essential feature of thisembodiment of endoscope is the maintenance of a fixed spatialrelationship between the flying spot kinescope 109a and the proximal end114a of the light conductor 114. The distal end 1141: of the lightconductor 114 also must be immobilized. The immobilization of thekinescope 109 and of the proximal end 114a of the light conductor wasdescribed above. The fixed spatial relationship between the distal end114b of the light conductor and Window 12 may be provided by rigid rods116a and 117a, or by enclosing the distal end of the light conductor ina rigid light-impervious box 147.

Furthermore, if no such box is used, there must be providedlight-impervious partitions 142 which prevent the light from the lightimage conductor 114 to reach the image sensitive element 131 beforebeing modulated and reflected by the examined part.

In some cases the flying spot kinescope 109 may be mounted inside of theendoscope or may be introduced inside of the examined body or object butwill remain outside of the endoscope.

In some cases the scanning illumination of the examined part is directedthrough the distal end of the endoscope as it is shown in FIG. 15a. Thelight from the light conductor 114, which may extend beyond theendoscope through the opening 151, is focused on the examined part bythe optical system 150. The reflected light is admitted into endoscopethrough windows 152 or 153 and is focused by lenses 152a or 153a on theimage sensitive member 131 or 131 a or both.

Another important improvement of all the endoscopes described above isthe use of a flexible source of illumination instead of conventional,rigid bulbs or lamps. The flexible light source 135 is illustrated inFIG. 16. The light source 135 comprises fluorescent layer 138, a lighttransparent conducting layer 137, another light transparent layerconducting layer 139. One of the conducting layers 137 and 139 may belight opaque instead of being light transparent. The layers 137 or 139may be continuous or preferably in the form of a fine mesh or grid. Thelayers 137 and 139 are connected to an extraneous source of A-C or DCelectrical potential, preferably, however, of AC type, The electricalpotential of l00-1,000 volts and frequency of 50 cycles per second up to1,000 cycles per second for AC type are suflicient to provide 10 ft.candles of illumination without producing any heat. This feature is ofgreat importance in examination of the living bodies where the heatgenerated by conventional filament type of bulbs may be injurious to theadjacent tissues. The fluorescent material is embedded in a dielectricmedium 1380. This dielectric medium must be of a flexible and lighttransparent material. Some of materials described above were found verysuitable for this purpose. In particular, polyesters, such as Mylar orCronar, silicones or terphalates, proved to be suitable for the purposesof this. invention.

The illuminescent materials used for the layer 138 are sulphides orselenides activated with copper or any other phosphors which haveelectroluminscent properties. The flexible light source 135 may be madeas a thin panel and may be disposed on the sidewalls or on the endwallof the endoscope.

The length of the flying spot kinescope 16a, 85 or 109 or any of itsmodifications is an important factor in the construction of endescopes.The rigid part of the flying spot tube is due to the electron gun 28 or90. Shortening of the electron gun would help therefor to reduce therigid part of the flying spot tube. In some cases it is pos-

